Asian Research Thesis Index

Abstract

Stevia rebaudiana Bertoni is considered as natural and non-toxic sucrose alternative that has ability to manage obesity and its associated diseases. Moreover, it is safe for human health and does not produce side effects. For the purpose, stevia leaves powder was characterized and stevioside (major glycoside in stevia due to which its taste is sweet) were extracted through different solvents (methanol, ethanol and water), purified and quantified by HPLC. Stevia extracts were also analyzed for physicochemical parameters.Regarding chemical composition, stevia leaves powder is rich source of both macronutrients and micronutrients. Ethanolic extract of stevia had high amount of antioxidants and stevioside as compared to methanolic and aqueous extracts of stevia. pH of ethanolic extract was less while total soluble sugars and total sugars were more than other extracts of stevia. In the product development phase, stevia leaves powder was utilized in the preparation of muffins and pure stevioside from aqueous stevia extract was incorporated in peach ready-to-serve beverages as sugar substitute. Both stevia muffins and stevioside from aqueous stevia extract containing RTS peach beverages were analyzed for phytochemical, physical and sensory analyses. The well-designed drinks were also subjected to all these analysis during two months storage period. Stevia improved the nutritional and antioxidant profile of both products. The physical and organoleptic evaluation parameters were affected significantly in muffins and beverages except pH and acidity. The antioxidant and physicochemical properties of stevioside containing RTS peach drinks were substantially affected and organoleptic evaluation parameters remained acceptable during storage. Animal studies were performed by varying the diets to investigate the anti-diabetic and hyperlipidemic potential of stevioside. In study I diabetes was induced in rats and then stevia aqueous extract was given to them and their anti-diabetic effect was compared with normal and diabetic control. In study II hypolipidemic potential of stevia aqueous extract was determined and compared with normal and hyperlipidemic controls. Stevia aqueous extract caused in momentous drop in body weights in both diabetic and hyperlipidemic rats. In the diabetic rats stevia significantly decreased the random, fasting blood glucose levels and HbA1c and elevated the insulin and glycogen contents. The total cholesterol, total triglycerides, low density lipoproteins, very low density lipoproteins levels and LDL/HDL ratio significantly decreased and high density lipoprotein level improved in hyperlipidemic rats taken stevia aquatic extract. ALT, AST and ALP significantly decreased and total weights ratios of body organs remained unaffected in both studies. Fromtheexistingexploration,itisassumedthat stevia aquatic extract is activein contradiction ofobesity,diabetes and hyperlipidemia.

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